Can't find the answer to 'get mountain climbing past US lake'.
Got all the letters in plus g as the penultimate. Gone brain dead. And even with all the help on 5ac. still unsolved.
15 is made up from 3 three-letter words, one reversed. I knew it as a camper van rather than a lake!
I can't see how to give a better hint for 5 than ginge's @2